INDIANAPOLIS—The chain of command was altered in late September with a phone call that drew the breath out of Bruce Arians.

An NFL assistant for two decades, he was about to be put in charge of his first professional team, the Indianapolis Colts. He had longed to be a head coach, or at least be considered for a position. But not under these circumstances.

Arians, 60, had spent the team’s bye week at his lakefront home in Georgia. On Sept. 30, while preparing to return to Indianapolis, his phone rang. It was coach Chuck Pagano.

“He called me at the lake," Arians said. “I was getting ready to go to the airport to get on the plane and come back. We’re talking and he sounded like he always did."

Then, everything changed.

“He said, ‘Oh, by the way, I went to the doctor and they told me I have leukemia,’ " Arians said. “I almost fell off the roof."

Pagano would take an indefinite leave. He would endure three rigorous rounds of chemotherapy, which ended Nov. 5.

While their coach fought for his life, his team fought on without him.

Arians has kept them on course. The Colts take a 9-4 record to Houston for a Sunday meeting with the Texans. They’re the tentative No. 5 seed in the AFC playoffs, one win from securing a postseason spot. Incredibly, the AFC South title remains in play.

While dealing with adversity that hit on a personal and professional level, the Colts have been motivated to extend the season to give Pagano an opportunity to return to the sideline. This year. Arians has pointed to the Dec. 30 regular-season finale against the Texans at Lucas Oil Stadium for his boss’ return.

That remains a real possibility.

"I’m fully supportive and I have my fingers crossed that he’ll be there on that sideline if that’s where he wants to be," said Dr. Larry Cripe of IU Health Simon Cancer Center. “It’s feasible. It’s possible. Is it definite? No. (But) I definitely think that’s where we’re heading, and we have our fingers crossed that ... he’s able to do it."

Pagano has remained involved in the daily activities of his team during his battle with leukemia. He and Arians talk regularly. He breaks down practice video, offers advice to players via texting.

Pagano has been an occasional visitor to the team complex and has attended the past three home games at Lucas Oil Stadium. He offered a passionate address in the locker room after the Nov. 4 win over Miami.

All that remains is for Pagano to regain his strength and stamina. If the team and his doctors clear him for a return this season, the plan is for Pagano to do so as head coach, not a figurehead on the sideline.

“If he comes back,’’ Arians said, “he’ll be the head coach and taking back over. I look forward to Chuck’s return, I really do. It has been an honor to be able to take over, and it’s been fun to have the chance to sit in that chair. But I can’t wait for the day that he comes back.

To appreciate what’s been accomplished thus far requires a quick reminder of last season’s 2-14 finish and the massive organizational overhaul that followed it. It’s not a stretch to consider how the season might have nose-dived after the news hit of Pagano’s battle with leukemia.

“Sure, it could have," Reggie Wayne said.

The Colts were 1-2 when informed of Pagano’s situation. Arians has directed them to an 8-2 record in Pagano’s absence, starting with an emotional 30-27 comeback victory over the Green Bay Packers on Oct. 7.

Wayne considers Pagano a close friend. They were together at the University of Miami, and it was Pagano who helped convince Wayne to re-sign with the Colts during the offseason.

And it was Wayne who quickly realized that if Pagano wasn’t to able to lead the team, Arians was the best stand-in.

“He’s kept it together because of the type of guy he is," Wayne said. “You know he’s the coach, but the type of person he is is what’s kept everything together. He came in and kept everything the same, didn’t change anything.

“And he didn’t change himself. He’s different. He’s not your average coach. There are some coaches that keep it blunt with you and some who keep it blunt. He’s the second blunt. In your face, telling you what it is."

“He’s just a straight-up dude," veteran defensive end Cory Redding said. “I like his approach ‘cause he keeps it real as far as telling guys that he holds them to a certain standard and he expects them to live up to it.

“He’s handling it way better than I thought he would, not knowing who he was or how he approached things, his philosophy. We’ve just followed his lead."

Arians has delegated some of the daily responsibilities, but has maintained his role as offensive coordinator while assuming so many of Pagano’s duties. On game day, he runs the entire show, including calling plays.

Arians routinely talks of how the events of the past several months have bonded the Colts, motivated them.

“This team found a purpose, unfortunately because our coach got sick and that’s a shame," he said. “He’s fighting for his life and it’s nothing more than asking, ‘How about we go fight for every game and extend this season until he can come back?’

“We have a date we’re all hoping that he can lead us down the tunnel on December 30 if all things go well, and if not we need to have this season extended until he can do that. I think that each man in the locker room, each coach and everybody in the Colts organization, is striving to do the same thing. When you have everybody on the same page and you take egos out of it, you play your best football."

Considering Arians’ impact on the season, it’s reasonable to wonder if he might finally get a chance to be a head coach once Pagano returns and normalcy returns to the Colts. He already is fielding calls from unemployed assistants asking him to put their name on his list for his staff in 2013.

At the very least, Arians will listen.

“My gosh, you’ve got to," he said. “But if they don’t have a quarterback or don’t have a chance to get one, that ain’t no fun, man. That’s a headache and ass firing waiting to happen.